The invention relates to dynamoelectric machines having commutators and brushes. More particularly, the invention relates to direct current electric motors and generators.
In such machines, very large currents flow between the carbon composition brushes and the commutator. Such large current flows result in localized heating due to the combination of resistive heating at the contact face and machine commutation. If sufficiently severe, change of state of materials may occur. This may cause electrical arcing with intense heating which will melt materials such as stainless steel in the brush holders and copper alloys in the commutators. It is therefore of great importance to prevent the creation of arcing between the portions of the brush holder and the commutator.
In the conventional design of many DC motors, a flange or similar member, which is a portion of the brush holder, supports the junction between the brush pigtail and the stator lead. The brush holder is commonly formed from stainless steel or some other electrically conductive material, and the flange or other portion of the brush holder supporting the junction is similarly constructed of electrically conductive material. In the known apparatus, arcing may develop between the commutator and the lower edge of the holder, which is in close proximity with the commutator, under conditions of especially heavy current through the machine. Arcing seriously damages the holders, brushes, and commutators and causes eventual failure of the machine. Thus, the brush holder may be distorted or altered in a manner which prevents the spring loaded brush it holds from being urged into full contact with the commutator.
The principal object of the invention is to provide a support for the junction between the brush pigtail and the stator lead to prevent damage to a dynamoelectric machine due to heavy current flow through the brushes.
An object of the invention is to provide a support for the junction between the brush pigtail and the stator lead which prevents damage of a dynamoelectric machine due to heavy current flow through the brushes by preventing arcing between the brush holder and the commutator.
Another object of the invention is to provide a support for the junction between the brush pigtail and the stator lead which prevents damage of a dynamoelectric machine due to heavy current flow through the brushes by preventing arcing between the brush holder and the commutator, without requiring major redesign of the machine.
Still another object of the invention is to provide a support for the junction between the brush pigtail and the stator lead, which support is installable with facility and convenience and is inexpensive in manufacture and installation, and prevents damage of a dynamoelectric machine due to having current flow through the brushes by preventing arcing between the brush holder and the commutator.
Yet another object of the invention is to provide a terminal from the brush pigtail to the junction with the stator lead of a dynamoelectric machine, which terminal prevents damage to the machine due to heavy current flow through the brushes by conducting maximum current.
Another object of the invention is to provide a terminal from the brush pigtail to the junction with the stator lead of a dynamoelectric machine, which terminal prevents damage to the machine due to heavy current flow through the brushes by conducting maximum current to avoid overheating.
Still another object of the invention is to provide a terminal from the brush pigtail to the junction with the stator lead of a dynamoelectric machine, which terminal is inexpensive in manufacture and installed and utilized in the same manner as known terminals of the same type, and which prevents damage to the machine due to heavy current flow through the brushes by conducting maximum current to avoid overheating.
Yet another object of the invention is to provide a brush for the commutator of a dynamoelectric machine, said brush assuring a good electrical connection of said brush to the junction with the stator lead of the machine.